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Daily Report #5180

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Old September 14th 10, 08:05 PM posted to sci.astro.hubble
Bassford, Lynn
external usenet poster
Posts: 44
Default Daily Report #5180

HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science


PERIOD COVERED: 5am September 13 - 5am September 14, 2010 (DOY 256/09:00z-257/09:00z)


Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be


12402 - COS 1021 STB Message received at 257/01:22z, following
successful GSAcq (2,1,1) at 257/01:15:46z, indicating take data flag
was down when a target acquisition macro was about to make a slew

Observations possibly affected: WFC3 20-21 Proposal ID#11905.



FGS GSAcq 7 7
FGS REAcq 9 9
OBAD with Maneuver 3 3



ACS/WFC 11996

CCD Daily Monitor (Part 3)

This program comprises basic tests for measuring the read noise and
dark current of the ACS WFC and for tracking the growth of hot pixels.
The recorded frames are used to create bias and dark reference images
for science data reduction and calibration. This program will be
executed four days per week (Mon, Wed, Fri, Sun) for the duration of
Cycle 17. To facilitate scheduling, this program is split into three
proposals. This proposal covers 308 orbits (19.25 weeks) from 21 June
2010 to 1 November 2010.

ACS/WFC 12210

SLACS for the Masses: Extending Strong Lensing to Lower Masses and
Smaller Radii

Strong gravitational lensing provides the most accurate possible
measurement of mass in the central regions of early-type galaxies
(ETGs). We propose to continue the highly productive Sloan Lens ACS
(SLACS) Survey for strong gravitational lens galaxies by observing a
substantial fraction of 135 new ETG gravitational-lens candidates with
HST-ACS WFC F814W Snapshot imaging. The proposed target sample has
been selected from the seventh and final data release of the Sloan
Digital Sky Survey, and is designed to complement the distribution of
previously confirmed SLACS lenses in lens-galaxy mass and in the ratio
of Einstein radius to optical half-light radius. The observations we
propose will lead to a combined SLACS sample covering nearly two
decades in mass, with dense mapping of enclosed mass as a function of
radius out to the half-light radius and beyond. With this longer mass
baseline, we will extend our lensing and dynamical analysis of the
mass structure and scaling relations of ETGs to galaxies of
significantly lower mass, and directly test for a transition in
structural and dark-matter content trends at intermediate galaxy mass.
The broader mass coverage will also enable us to make a direct
connection to the structure of well-studied nearby ETGs as deduced
from dynamical modeling of their line-of-sight velocity distribution
fields. Finally, the combined sample will allow a more conclusive test
of the current SLACS result that the intrinsic scatter in ETG
mass-density structure is not significantly correlated with any other
galaxy observables. The final SLACS sample at the conclusion of this
program will comprise approximately 130 lenses with known foreground
and background redshifts, and is likely to be the largest confirmed
sample of strong-lens galaxies for many years to come.

ACS/WFC 12292

SWELLS: Doubling the Number of Disk-dominated Edge-on Spiral Lens

The formation of realistic disk galaxies within the LCDM cosmology is
still largely an unsolved problem. Theory is now beginning to make
predictions for how dark matter halos respond to galaxy formation, and
for the properties of disk galaxies. Measuring the density profiles of
dark matter halos on galaxy scales is therefore a strong test for the
standard paradigm of galaxy formation, offering great potential for
discovery. However, the degeneracy between the stellar and dark matter
contributions to galaxy rotation curves remains a major obstacle.
Strong gravitational lensing, when combined with spatially resolved
kinematics and stellar population models, can solve this long-standing
problem. Unfortunately, this joint methodology could not be exploited
until recently due to the paucity of known edge-on spiral lenses. We
have developed and demonstrated an efficient technique to find exactly
these systems. During supplemental cycle-16 we discovered five new
spiral lens galaxies, suitable for rotation curve measurements. We
propose multi-color HST imaging of 16 candidates and 2
partially-imaged confirmed systems, to measure a sample of eight new
edge-on spiral lenses. This program will at least double the number of
known disk-dominated systems. This is crucial for constraining the
relative contribution of the disk, bulge and dark halo to the total
density profile.

ACS/WFC3 11734

The Hosts of High Redshift Gamma-Ray Bursts

Gamma-ray bursts are the most luminous explosive events known, acting
as beacons to the high redshift universe. Long duration GRBs have
their origin in the collapse of massive stars and thus select star
forming galaxies across a wide range of redshift. Due to their bright
afterglows we can study the details of GRB host galaxies via
absorption spectroscopy, providing redshifts, column densities and
metallicities for galaxies far too faint to be accessible directly
with current technology. We have already obtained deep ground based
observations for many hosts and here propose ACS/WFC3 and WFC3
observations of the fields of bursts at z3 which are undetected in
deep ground based images. These observations will study the hosts in
emission, providing luminosities and morphologies and will enable the
construction of a sample of high-z galaxies with more detailed
physical properties than has ever been possible before.

STIS/CCD 11845

CCD Dark Monitor Part 2

Monitor the darks for the STIS CCD.

STIS/CCD 11847

CCD Bias Monitor-Part 2

Monitor the bias in the 1x1, 1x2, 2x1, and 2x2 bin settings at gain=1,
and 1x1 at gain = 4, to build up high-S/N superbiases and track the
evolution of hot columns.


Cosmo-chronometry and Elemental Abundance Distribution of the Ancient
Star HE1523-0901

We propose to obtain near-UV HST/STIS spectroscopy of the extremely
metal-poor, highly r-process-enhanced halo star HE 1523-0901, in order
to produce the most complete abundance distribution of the heaviest
stable elements, including platinum, osmium, and lead. These HST
abundance data will then be used to estimate the initial abundances of
the long-lived radioactive elements thorium and uranium, and by
comparison with their observed abundances, enable an accurate age
determination of this ancient star. The use of radioactive
chronometers in stars provides an independent lower limit on the age
of the Galaxy, which can be compared with alternative limits set by
globular clusters and by analysis from WMAP. Our proposed observations
of HE1523-0901 will also provide significant new information about the
early chemical history of the Galaxy, specifically, the nature of the
first generations of stars and the types of nucleosynthetic processes
that occurred at the onset of Galactic chemical evolution.

STIS/CCD/MA1 11737

The Distance Dependence of the Interstellar N/O Abundance Ratio: A
Gould Belt Influence?

The degree of elemental abundance homogeneity in the interstellar
medium is a function of the enrichment and mixing processes that
govern galactic chemical evolution. Observations of young stars and
the interstellar gas within ~500 pc of the Sun have revealed a local
ISM that is so well-mixed it is having an impact on ideas regarding
the formation of extrasolar planets. However, the situation just
beyond the local ISM is not so clear. Sensitive UV absorption line
measurements have recently revealed a pattern of inhomogeneities in
the interstellar O, N, and Kr gas-phase abundances at distances of
~500 pc and beyond that appear nucleosynthetic in origin rather than
due to dust depletion. In particular, based on a sample of 13
sightlines, Knauth et al. (2006) have found that the nearby stars (d
500 pc) exhibit a mean interstellar N/O abundance ratio that is
significantly higher (0.18 dex) than that toward the more distant
stars. Interestingly, all of their sightlines lie in the sky vicinity
of the Gould Belt of OB associations, molecular clouds, and diffuse
gas encircling the Sun at a distance of ~400 pc. Is it possible that
mixing processes have not yet smoothed out the recent ISM enrichment
by massive stars in the young Belt region? By measuring the
interstellar N/O ratios in a strategic new sample of sightlines with
STIS, we propose to test the apparent N/O homogeneity inside the Gould
Belt and determine if the apparent decline in the N/O ratio with
distance is robust and associated with the Belt region.

STIS/MA1/MA2 11857

STIS Cycle 17 MAMA Dark Monitor

This proposal monitors the behavior of the dark current in each of the
MAMA detectors.

The basic monitor takes two 1380s ACCUM darks each week with each
detector. However, starting Oct 5, pairs are only included for weeks
that the LRP has external MAMA observations planned. The weekly pairs
of exposures for each detector are linked so that they are taken at
opposite ends of the same SAA free interval. This pairing of exposures
will make it easier to separate long and short term temporal
variability from temperature dependent changes.

For both detectors, additional blocks of exposures are taken once
every six months. These are groups of five 1314s FUV-MAMA Time-Tag
darks or five 3x315s NUV ACCUM darks distributed over a single
SAA-free interval. This will give more information on the brightness
of the FUV MAMA dark current as a function of the amount of time that
the HV has been on, and for the NUV MAMA will give a better measure of
the short term temperature dependence.

WFC3/IR 12265

Determining the Physical Nature of a Unique Giant Lya Emitter at

We propose deep WFC3/IR imaging for a giant Lya emitter (LAE) with a
Keck spectroscopic redshift of z=6.595 discovered by extensive
narrow-band imaging with Subaru in the SXDS-UKIDSS/UDS field. This
remarkable object is unique in many respects including its large
stellar mass and luminous nebula which extends over 17 kpc; no
equivalent source has been found in other surveys. The nature of this
rare object is unclear. Fundamental to progress is determining the
origin of star formation in such an early massive object; if the age
of the stellar population is short we are likely witnessing a special
moment in the formation history of a massive galaxy. The heating
source for the nebula is also unclear; options include intense star
formation, the infall of cold gas onto a dark halo or shock heating
from a merger. We will take deep broad-band (F125W and F160W) images
and an intermediate-band (F098M) image which will be analyzed in
conjunction with ultra-deep IRAC 3.6 and 4.5 micron data being taken
by the Spitzer/SEDS project. These data will enable us to constrain
the star formation rate and stellar age. Moreover, the UV continuum
morphology and Lya-line distribution will be investigated for evidence
of a major merger, cold accretion, or hot bubbles associated with
outflows. We will address the physical origin of the remarkable object
observed at an epoch where massive galaxies are thought to begin their

WFC3/IR/S/C 11929

IR Dark Current Monitor

Analyses of ground test data showed that dark current signals are more
reliably removed from science data using darks taken with the same
exposure sequences as the science data, than with a single dark
current image scaled by desired exposure time. Therefore, dark current
images must be collected using all sample sequences that will be used
in science observations. These observations will be used to monitor
changes in the dark current of the WFC3-IR channel on a day-to-day
basis, and to build calibration dark current ramps for each of the
sample sequences to be used by Gos in Cycle 17. For each sample
sequence/array size combination, a median ramp will be created and
delivered to the calibration database system (CDBS).

WFC3/UVIS 11905

WFC3 UVIS CCD Daily Monitor

The behavior of the WFC3 UVIS CCD will be monitored daily with a set
of full-frame, four-amp bias and dark frames. A smaller set of 2Kx4K
subarray biases are acquired at less frequent intervals throughout the
cycle to support subarray science observations. The internals from
this proposal, along with those from the anneal procedure (Proposal
11909), will be used to generate the necessary superbias and superdark
reference files for the calibration pipeline (CDBS).

WFC3/UVIS 11914

UVIS Earth Flats

This program is an experimental path finder for Cycle 18 calibration.
Visible-wavelength flat fields will be obtained by observing the dark
side of the Earth during periods of full moon illumination. The
observations will consist of full-frame streaked WFC3 UVIS imagery:
per 22- min total exposure time in a single "dark-sky" orbit, we
anticipate collecting 7000 e/pix in F606W or 4500 e/pix in F814W. To
achieve Poisson S/N 100 per pixel, we require at least 2 orbits of
F606W and 3 orbits of F814W.

For UVIS narrowband filters, exposures of 1 sec typically do not
saturate on the sunlit Earth, so we will take sunlit Earth flats for
three of the more-commonly used narrowband filters in Cycle 17 plus
the also-popular long-wavelength quad filters, for which we get four
filters at once.

Why not use the Sunlit Earth for the wideband visible-light filters?
It is too bright in the visible for WFC3 UVIS minimum exposure time of
0.5 sec. Similarly, for NICMOS the sunlit-Earth is too bright which
saturates the detector too quickly and/or induces abnormal behaviors
such as super-shading (Gilmore 1998, NIC 098-011). In the narrowband
visible and broadband near- UV is not too bright (predictions in Cox
et al. 1987 "Standard Astronomical Sources for HST: 6. Spatially Flat
Fields." and observations in ACS Program 10050).

Other possibilities? Cox et al.'s Section II.D addresses many other
possible sources for flat fields, rejecting them for a variety of
reasons. A remaining possibility would be the totally eclipsed moon.
Such eclipses provide approximately 2 hours (1 HST orbit) of
opportunity per year, so they are too rare to be generically useful.
An advantage of the moon over the Earth is that the moon subtends less
than 0.25 square degree, whereas the Earth subtends a steradian or
more, so scattered light and light potentially leaking around the
shutter presents additional problems for the Earth. Also, we're unsure
if HST can point 180 deg from the Sun.

WFC3/UVIS/IR 11909

UVIS Hot Pixel Anneal

The on-orbit radiation environment of WFC3 will continually generate
new hot pixels. This proposal performs the procedure required for
repairing those hot pixels in the UVIS CCDs. During an anneal, the
two-stage thermo-electric cooler (TEC) is turned off and the
four-stage TEC is used as a heater to bring the UVIS CCDs up to ~20
deg. C. As a result of the CCD warmup, a majority of the hot pixels
will be fixed; previous instruments such as WFPC2 and ACS have seen
repair rates of about 80%. Internal UVIS exposures are taken before
and after each anneal, to allow an assessment of the procedure's
effectiveness in WFC3, provide a check of bias, global dark current,
and hot pixel levels, as well as support hysteresis (bowtie)
monitoring and CDBS reference file generation. One IR dark is taken
after each anneal, to provide a check of the IR detector.


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